This paper reports the crack growth behavior of pipeline steels in near-neutral pH environments. Crack growth data both from laboratory tests using compact tension (CT) specimen and from full scale tests of shallow cracks were analyzed using a true corrosion-fatigue model established recently. It has been found that the crack growth rate can be correlated with ΔK2Kmax/fα, where ΔK is the stress intensity factor range; Kmax is the maximum stress intensity factor; f is the loading frequency; and α is a factor related to corrosivity of soil environments. This correlation enables determination of threshold ΔK2Kmax/fα values for long cracks such as in a test using CT specimen. The above growth correlation appears also true for small/shallow cracks in full scale tests except that small/shallow cracks were found to grow at appreciable rates below the threshold of long/deep cracks. Implications of the growth model to crack growth occurring in the field and pipe integrity management were also discussed in the paper.

This content is only available via PDF.
You do not currently have access to this content.